Need some help please VZ 2004 SS Ute - rough idling and SVS code

[murf58]

Having some issues with my Ute - has a full service history with 175km.

- running very rough in the morning (cold here on the New England tablelands), idling all over the place - surging to just below 2000rpm
- giving an SVS code - goes off bout 4-7 times and seems to stop once at operating temperature
- no codes showing on two different scanners (One was a snap on used by a mechanics shop)
- when warm, sometimes idles pretty smoothly with just a hint of a bit of a misfire. However recently the misfire and rough idling seems to be happening more often when warm

Ive done the following in the last 2 months (Had a mechanic mate helping who did the work)
* new spark plugs and leads
* new fuel filter
* replaced oil pressure sensor (read here it is often the cause of the SVS code)
* checked/cleaned MAF sensor and throttle body (both were spotless)

I’ve searched all the rough idling threads here and am thinking of replacing the O2 sensors and/or the coil packs next.
starting to get a bit frustrated so thought I would see if anyone can help what to focus on next or if I am missing something.
‘thanks

 

[Fu Manchu]

A smoke test should be done to find the vacuum leaks. It will be a near 100% concussive way of finding them. A laser pointer or torch will find the tiny ones.

Clean the PCV. There’s a thread on it. Do the modification. It’s near on essential for everyone. Plan to have the two PCV hoses replaced or farnarkle the ends to have new hose on just the ends.

With heat being a common denominator, the smoke test should be done on a cold engine.

Do a vacuum test on the HVAC system. That is done via the little tube going from the intake plenum to the firewall. You could disconnect that, fold it over, cable tie it from the back of the plenum, and isolate the vacuum see if the problem persists.

Plan to replace the lower intake gasket. Plan to replace the intake plenum gasket. Use metal ones, not paper. Throttle body gasket, have one ready.

Remove the negative terminal on the battery. Isolate it. Then:

Clean the cam actuators. Carby/throttle body cleaner. They are an easy thing to remove. Inspect the seals for leaks.

Clean the cam sensors. Paper towel. Throttle body cleaner. Same deal. Inspect the sensors.

Clean all the earths on the car under the bonnet. (With negative terminal isolated away from the battery) Physically remove each one. Clean it. A little brass brush is ideal. Clean the threads on the bolt. Focus on all mating surfaces. The eyelet, the chassis or engine and the bolt itself. Spray out the parts with deoxit or CO Contact cleaner. Snug up each bolt. Remove the battery. Behind there is a major harness earth point. A plug with lots of earths to the chassis. Clean the pins as best you can. Clean the bolt hole and bolt holding the other part of the plug to the chassis.

Service the injectors. Clean them. Put new filters and o-rings. You can buy kits for them.

Lastly there is also the possibility that there is a mechanical reason for the idle, but do the easy serviceable things first. All good practice regardless.

 

[murf58]

Awesome - thanks Fu Manchu, exactly what I was looking for.
challenge will be finding a mechanic with a vacuum and smoke testing machine in a relatively small country town but I’ll ask around. I’ll get onto the PCV and cam sensors/actuators this weekend. Appreciate the advice thank you.

 

[Fu Manchu]

I made a smoke tester. Works really well.

 

[krusing]

Having some issues with my Ute - has a full service history with 175km.

- running very rough in the morning (cold here on the New England tablelands), idling all over the place - surging to just below 2000rpm
- giving an SVS code - goes off bout 4-7 times and seems to stop once at operating temperature
- no codes showing on two different scanners (One was a snap on used by a mechanics shop)
- when warm, sometimes idles pretty smoothly with just a hint of a bit of a misfire. However recently the misfire and rough idling seems to be happening more often when warm

Ive done the following in the last 2 months (Had a mechanic mate helping who did the work)
* new spark plugs and leads
* new fuel filter
* replaced oil pressure sensor (read here it is often the cause of the SVS code)
* checked/cleaned MAF sensor and throttle body (both were spotless)

I’ve searched all the rough idling threads here and am thinking of replacing the O2 sensors and/or the coil packs next.
starting to get a bit frustrated so thought I would see if anyone can help what to focus on next or if I am missing something.
‘thanks

You don’t need to replace any parts that do not need replacing,
Yes, I can understand the frustration,
You just need to go through the fault process to eliminate the fault.

ie: O2 sensors, if they are not playing up/broken,
Or causing DTC’s.
Don’t fix them if they are not broken.

 

[Fu Manchu]

The other thing to understand is that fault codes are not shopping lists.

If a sensor sets a code it’s because its set parameters have been exceeded. There can be circumstances other than that sensor being faulty causing that. Actual mechanical issues or other sensors elsewhere not setting codes or wiring faults, connector damage or module faults. The list goes on and on.